Coupling unit

Abstract

In order to provide a coupling unit for a trailer coupling of a motor vehicle comprising a coupling ball and a coupling ball carrier carrying the coupling ball with the aid of which the loads effective thereon when in use can be detected in a reliable and simple manner, it is proposed that the coupling unit comprise a load-bearing structure which engages around a channel extending parallel to an axis, and that a reference finger extending from a first end to a second end in a longitudinal direction approximately parallel to the axis be arranged in the channel, wherein said finger is fixed at the first end such as to be static relative to the load-bearing structure and extends such as to be free from deformations of the load-bearing structure up to the second end, and wherein the second end cooperates with a sensor unit which detects a relative position of the second end relative to a region of the load-bearing structure engaging around it.

The invention claimed is: 
     
       1. Coupling unit for a trailer coupling of a motor vehicle comprising a coupling ball and a coupling ball carrier carrying the coupling ball, the coupling unit comprises a load-bearing structure, a portion of the load bearing structure engages around a channel extending parallel to an axis, a reference finger extending from a first end to a second end in a longitudinal direction approximately parallel to the axis is arranged in the channel, wherein said finger is fixed at the first end such as to be static relative to the portion of the load-bearing structure forming the channel, and extends such as to be free from deformations of the load-bearing structure up to the second end, and in that the second end cooperates with a sensor unit which detects a relative position of the second end relative to a region of the load-bearing structure engaging around said second end and in a direction transverse to the extension in the longitudinal direction of the reference finger. 
     
     
       2. A coupling unit in accordance with  claim 1 , wherein the load-bearing structure engages around the channel in U-shaped manner. 
     
     
       3. A coupling unit in accordance with  claim 1 , wherein the load-bearing structure completely engages around the channel at least in sections. 
     
     
       4. A coupling unit in accordance with  claim 3 , wherein the load-bearing structure is a structure which encompasses the channel and is closed in a circumferential direction. 
     
     
       5. A coupling unit in accordance with  claim 1 , wherein the reference finger extends in the channel in non-contacting manner relative to the load-bearing structure from the first end up to the second end. 
     
     
       6. A coupling unit in accordance with  claim 1 , wherein the reference finger is an inherently stiff structure which keeps the second end positioned rigidly or in bending-resistant manner relative to the first end. 
     
     
       7. A coupling unit in accordance with  claim 1 , wherein the reference finger is in the form of a bar. 
     
     
       8. A coupling unit in accordance with  claim 1 , wherein the sensor unit comprises at least one spacing sensor. 
     
     
       9. A coupling unit in accordance with  claim 8 , wherein the spacing sensor is fixed to the load-bearing structure. 
     
     
       10. A coupling unit in accordance with  claim 8 , wherein the sensor unit comprises the at least one spacing sensor and a second spacing sensor which detect a spacing of the second end from the load-bearing structure in different spatial directions. 
     
     
       11. A coupling unit in accordance with  claim 8 , wherein the sensor unit comprises the at least one spacing sensor and a second spacing sensor, the first and second spacing sensors in opposed space relation for detecting a relative movement of the second end relative to the load-bearing structure in one spatial direction. 
     
     
       12. A coupling unit in accordance with  claim 8 , wherein the sensor unit comprises the at least one spacing sensor and a second spacing sensor s for detecting a relative movement between the second end and the load-bearing structure in each spatial direction. 
     
     
       13. A coupling unit in accordance with  claim 1 , wherein the channel is arranged exclusively in the coupling ball carrier and in that the load-bearing structure is formed by a section of the coupling ball carrier engaging around the channel. 
     
     
       14. A coupling unit in accordance with  claim 1 , wherein the channel passes through the coupling ball and a region thereof adjoining the first end of the coupling ball carrier. 
     
     
       15. A coupling unit in accordance with  claim 1 , wherein the channel passes through a ball-base extension of the coupling ball carrier which carries the coupling ball. 
     
     
       16. A coupling unit in accordance with  claim 1 , wherein the channel passes through the coupling ball, a ball-base extension and a region of the coupling ball carrier which is located on a side of the ball-base extension opposite the coupling ball and adjoined thereto. 
     
     
       17. A coupling unit in accordance with  claim 16 , wherein the load-bearing structure also comprises at least a part of the coupling ball. 
     
     
       18. A coupling unit in accordance with  claim 16 , wherein the load-bearing structure comprises at least one region of the coupling ball carrier that is of widened cross-section. 
     
     
       19. A coupling unit in accordance with  claim 1 , wherein at least a ball-base extension forms the load-bearing structure that is deformable by the load on the coupling ball. 
     
     
       20. A coupling unit in accordance with  claim 1 , wherein the reference finger is arranged such that the first end thereof is fixed relative to the coupling ball. 
     
     
       21. A coupling unit in accordance with  claim 20 , wherein the reference finger is arranged such that the first end thereof is fixed relative to the region of widened cross-section of the coupling ball carrier. 
     
     
       22. A coupling unit in accordance with  claim 1 , wherein the sensor unit is coupled to an evaluating unit which recognizes a load-free state of the coupling unit and detects a spacing from the second end of the reference finger in the load-free state and, based upon said load-free state, determines a force on the coupling ball from a relative change in spacing between the second end and the load-bearing structure taken with reference to the load-free state. 
     
     
       23. A coupling unit in accordance with  claim 22 , wherein a calibration curve specific to the coupling unit is stored in the evaluating unit and by means thereof, the determined force effective upon the coupling ball is effected from the changes in the spacing. 
     
     
       24. The coupling unit of  claim 1 , wherein the load bearing structure is a coherent load bearing structure such that no part of the load bearing structure is rotatable relative to another part of the load-bearing structure. 
     
     
       25. Coupling unit for a trailer coupling of a motor vehicle comprising a coupling ball and a coupling ball carrier carrying the coupling ball, the coupling ball fixed relative to the coupling ball carrier, the coupling unit comprises a load bearing structure which engages around a channel extending parallel to an axis, a reference finger extending from a first end to a second end in a longitudinal direction approximately parallel to the axis is arranged in the channel, wherein said finger is fixed at the first end such as to be static relative to load-bearing structure, and extends such as to be free from deformations of the load-bearing structure up to the second end, and in that the second end cooperates with a sensor unit which detects a relative position of the second end relative to a region of the load-bearing structure engaging around said second end.